<Page
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
  <StackPanel Orientation="Horizontal">
      <StackPanel Orientation="Horizontal">  
        <Button VerticalAlignment="Top">Button1</Button>
        <Button VerticalAlignment="Center">Button2</Button>
        <Button VerticalAlignment="Bottom">Button3</Button>
        <Button>Button4</Button>
      </StackPanel>
      <StackPanel Orientation="Vertical">  
        <Button HorizontalAlignment="Center">Button1</Button>
        <Button HorizontalAlignment="Left">Button2</Button>
        <Button HorizontalAlignment="Right">Button3</Button>
        <!--default alignment is stretch-->
        <Button Width="500" Padding="10,10,10,10">Button4</Button><!--though strech, but it cannot occupy the whole row-->
      </StackPanel>
    </StackPanel>
</Page>